The global monsoon system plays a vital role in shaping ecosystems, agriculture, and economies across large parts of the world. In the context of climate change, understanding how land water availability—measured as precipitation minus evaporation (P–E)—will evolve is critical for ensuring sustainable development and environmental protection across monsoon-affected regions.

While previous studies, including the Intergovernmental Panel on Climate Change’s Sixth Assessment Report (IPCC AR6), have largely focused on greenhouse gas (GHG)-driven trends, a new study by researchers at the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, reveals the equally important role of aerosol reduction in driving future changes in P–E across global monsoon regions.

Published in Science Bulletin on July 16, the study examines changes in P–E from 1951 to 2100, with future projections based on a mid-range emissions scenario (SSP2-4.5). It finds that both rising GHG concentrations and shifts in the core regions of anthropogenic aerosol (AA) emissions drive long-term trends and regional variability in P–E across global and regional monsoon domains.

The findings suggest a complex future: Escalating GHG concentrations are projected to increase P–E across the Asian–African monsoon domains while decreasing P–E in the American monsoon domains. Conversely, aerosol reductions will drive a transition from the current widespread drying to future wetting, with contributions comparable to GHG forcing over the Asian–African monsoon domains. These diverse regional patterns of precipitation change arise from dynamic processes related to atmospheric circulation shifts and aerosol–cloud interactions, as both the increase in GHG concentrations and the decrease in AA emissions can enhance atmospheric moisture content and strengthen thermodynamic processes.

This research offers crucial insights for climate policy and water resource management. “While many studies have highlighted the critical impact of greenhouse gases on the water cycle, our study emphasizes the importance of considering both carbon neutrality and clean air policies when addressing future water resource challenges—especially in densely populated monsoon regions,” said Dr. Jiang Jie, first author of the study.